This invention is in the field of fluid control devices. More specifically it is related to ball type valves used for the control of fluids. Still more specifically it is particularly adapted for use in the gas industry to shut off gas flow lines, such as those from a main line to a residence.
One problem with the prior art type of ball valves is that the mechanism for forcing the ball onto the valve seat must be accurately machined, otherwise a firm seat is not achieved. If too much force is applied on the ball against the seat either the seat or the ball will be damaged. Any permanent deformation of the ball or seat will result in leakage upon subsequent seating of the ball. Therefore the design and manufacture of a successful ball valve has required very accurate machining tolerances. In addition, in the prior art devices the ball control element, which urges the ball onto the seat has caused a reduction in the pressure of the ball against the seat, reducing the sealing effectiveness of the valve.
Conventional ball valves usually require rubber, plastic or other compliant material to obtain the necessary seal resiliency. This is a serious detriment in gas service since a fire can cause the rubber or plastic seat to melt, resulting in valve failure. The valve of this invention eliminates this problem by providing a metal to metal resilient seat. In addition, many conventional ball valves require an expensive ball construction, having a slot formed through the center of the ball for passing of fluid. This invention provides a valve having a solid ball, which is much less expensive to manufacture.
To overcome basic problems of ball type valves, that is, accuracy of machining and manufacture, and leakage caused by wear of the parts, this invention provides a resilient means of urging the ball onto the seat. Such resilient means compensates for inaccuracies in manufacturing and for wear of components. The resilient arrangement obviates the possibility of damaging the ball or the seat and causing potential leakage of the valve. In addition wear is compensated by the resilient means within the valve.